CHICAGO -- A new school year starts tomorrow with CPS touting additional safe passage routes and an improved graduation rate.

But big budget problems and the strong possibility of a teachers strike are looming.

Mayor Emanuel and CPS officials tried to emphasize good news Monday ahead of the start of the school year.

The mayor mingled with students while touring the new annex at Walter Payton College Prep. The high school has added 17 more classrooms plus a modern gymnasium, acting facility and dance studio.

This early look comes as CPS announces that its latest five-year graduation is up. It now stands at 73.5 percent.

“ It’s the highest graduation rate in the history of Chicago Public Schools,” Emanuel said.

The 73.5 percent is a few points better than the 69.9 percent during the 2014-2015 school year. And it’s 16 percentage points higher than five years ago.

This school year starts just as the last one ended with the district managing financial issues and the threat of another teacher strike. Today, CPS CEO Forrest Claypool was not ready to discuss a contingency plan if the teachers walk off the job.

“We’re engaged in very intensive negotiations,” Claypool said. “Now that Labor Day is over we feel like those talks will intensify with the teachers union and we’re looking forward to continuing those talks.”